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Fluid Journal : Fluid Journal 2005-2007
Early Spring 2005 Fluid Journal 2 We realized that most Texas rice farmers use some of these innovations, but few used the complete package of cost- saving production practices available. The upside of fluids N in plant. Banding fluid and broadcasting dry N at 150 lbs/ A at planting, plus early flood irrigation at the 6-leaf stage, improved midseason N in rice plants when all N fertilizer was applied at planting. Midseason N content of fluid-banded plants was 90 lbs/A. N content of plants receiving all dry broadcast fertilizer contained only 66 lbs/A. The additional 27 lbs/A of N in the fl uid-applied plants was the result of increased N uptake by banding fl uid N compared to broadcasting dry N. Flood irrigation at the 4-leaf stage increased N uptake across all treatments. Plant N uptake was 103 lbs/A for banded fluid and 82 lbs/A for plants receiving dry applications at planting. Yield. Figure 1 shows that the check treatment yielded 2,100 lbs/A when flooded at 4-leaf and 1,500 lbs/A when flooded at the 6-leaf stage. The 600-lb/A advantage with 4-leaf flood suggests this stage improved conditions for maximizing rice yield and/or increasing soil N uptake efficiency. The 4-leaf flood also maximized yields of all treatments when fertilizer was applied. When 150 lbs/A of N were applied under the 4-leaf flood stage, the 3-way split of dry fertilizer yielded 6,400 lbs/A, while both dry and fl uid fertilizer applied all preplant yielded 6,900 lbs/A. Under 6-leaf flood the 3-way split of dry fertilizer yielded 5,800 lbs/A while all the all-preplant dry and preplant fluid yielded only 5,200 and 6,200 lbs/A, respectively. Thus, the more efficient banded fluid N produced higher rice yields than the dry N under 6-leaf flood where conditions were more favorable for N denitrification. Banded fluid would likely have produced higher yields than the all-preplant dry N under the 4-leaf flood stage even if the N rate had been lower than 150 lbs/A. Economics 6-leaf flood. As shown earlier, banded fluid N yielded 6,200 lbs/A, which was 400 lbs/A more than the best dry fertilizer treatment (i.e., the 3-way split yielding 5,800 lbs/A). The 400-lb/A higher yield represented an income improvement of $32/A. Estimated application cost for banded fluid N was no more than $6/A compared to at least $25/A for the 3-way split dry. This represented a $19/A reduction in application cost. Therefore, total per acre advantage for banded fluid over dry was estimated at $51/A ($19 + $32/A). 4-leaf flood. As shown earlier, banded fl uid N yielded 6,900 lbs/A, which was about 500 lbs/A higher than the 6,400 lbs/A yield of the 3-way split dry N. That would create about a $40/A advantage for banded fl uid N verses dry N, based on $8/cwt of rice. Thus, banded fluid N would have a $19/A Figure 1. Rice grain yield for standard and early flood, comparing dry versus fluid N. When fluid N was applied as a 3-way split, only the PP application was fluid. The PF and PD application was dry.
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